Curable silicone composition, cured product thereof, and optical semiconductor device

Abstract

The present invention relates to a curable silicone composition comprising: (A) an organopolysiloxane represented by the average unit formula: (RSiO)(RSiO)(RSiO)(RSiO), wherein, Rare the same or different alkyl groups having from 1 to 12 carbons, alkenyl groups having from 2 to 12 carbons, aryl groups having from 6 to 20 carbons, or aralkyl groups having from 7 to 20 carbons, provided that at least two Rin a molecule are the alkenyl groups; Ris an aryl group having from 6 to 20 carbons or an aralkyl group having from 7 to 20 carbons; Ris an alkyl group having from 1 to 12 carbons; and a, b, c, and d are respectively numbers satisfying: 0.01≦a≦0.5, 0≦b≦0.7, 0.01≦c<0.7, 0.1≦d<0.9, and a+b+c+d=1; (B) a linear organopolysiloxane having at least two silicon-bonded alkenyl groups and at least one silicon-bonded aryl group in a molecule; (C) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule; (D) a hydrosilylation-reaction catalyst. The curable silicone composition has excellent handling/workability and forming a cured product with a high refractive index and low gas permeability when cured.